CacheLinePad.java

/*
 * Copyright (c) 2002-2011 LWJGL Project
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 * * Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * * Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 *
 * * Neither the name of 'LWJGL' nor the names of
 *   its contributors may be used to endorse or promote products derived
 *   from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.lwjgl.util.mapped;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * When this annotation is used on a field, automatic cache-line-sized padding
 * will be inserted around the field. This is useful in multi-threaded algorithms
 * to avoid cache line false sharing. The annotation defaults to padding after
 * the field, but can be changed to before or both before and after. It can be
 * applied to both mapped object fields and POJO primitive fields.
 *
 * @author Spasi
 */
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
public @interface CacheLinePad {

	/**
	 * When true, cache-line padding will be inserted before the field.
	 *
	 * @return true if cache-line padding will be inserted before the field
	 */
	boolean before() default false;

	/**
	 * When true, cache-line padding will be inserted after the field.
	 *
	 * @return true if cache-line padding will be inserted after the field
	 */
	boolean after() default true;

}